Terminal Apparatus and Method of Controlling Terminal Apparatus with Multi-Tasking Features

1. A terminal apparatus comprising: circuitry configured to: store a plurality of application programs each having computer readable instructions, said plurality of application programs including a first application program and a second application program; execute instructions of the first application program; display a screen generated by the circuitry when executing the first application program; store data on the first application program when an operation of the first application program is paused; and respond to an external input by changing the screen to a screen image of the second application program, said external input including a dragging operation of an external device so as to pause the first application program, wherein in response to the circuitry receiving the external input, the circuitry causes image data generated for the first application program while being executed and data of an execution state of the first application program to be stored for subsequent retrieval when resuming execution of said first application program into the circuitry, the circuitry simultaneously displays a partial screen image for the first application program with a partial screen image of the second application program prior to fully transitioning to a display of an entirety of the screen image for the second application program, the circuitry gradually increases a display area of the screen image for the second application program in accordance with the dragging operation, the circuitry places the second application program into an execution state when the display area of the screen image for the second application program is more than a predetermined threshold, in a case that another external input is not detected by the circuitry within a predetermined time period of displaying the entirety of the screen image for the second application program, the circuitry begins execution of the second application program, and in a case that another external input is detected by the circuitry within the predetermined time period, the circuitry does not begin execution of the second application program and the circuitry subsequently begins execution of a different application program.

2. The apparatus of claim 1 , wherein: when the circuitry receives an external input signal indicating a change to a display of the image data generated for the first application program while in execution, the circuitry responds by changing a currently displayed screen to the screen of the first application program, the screen of the first application program representing one of an initial screen image of the first application program and a screen image of a state of execution at a time when said circuitry caused said image data generated for the first application program to be stored.

3. The apparatus of claim 1 , wherein: the circuitry executes instructions for said second application program when the circuitry responds to said external input by placing said second application program into an execution state.

4. The apparatus of claim 3 , wherein: the circuitry continues execution of instructions of said first application program after the circuitry causes the circuitry to begin execution of instructions for said second application program.

5. The apparatus of claim 3 , wherein: when the circuitry executes the instructions for the second application program, the first application program changes to a paused state, and the circuitry displays the screen image for the second application program while in an execution state.

6. The apparatus of claim 1 , wherein: said plurality of application programs have respective priorities assigned thereto, and in response to said external input, screen images for said plurality of application programs that are in one of a paused state and an execution state are displayed in priority order.

7. The apparatus of claim 1 , wherein: in response to said external input, respective screen images of said plurality of application programs that have been paused are displayed in an order by which said plurality of application programs were paused.

8. The apparatus of claim 1 , wherein: respective screen images of said plurality of application programs that have been paused are displayed in a reverse order in which said plurality of application programs were paused.

9. A method for controlling a terminal apparatus that manages a plurality of application programs, comprising: storing in a non-transitory computer readable medium a plurality of application programs each having computer readable instructions, said plurality of application programs including a first application program and a second application program; executing, using circuitry, instructions of the first application program so as to put the first application program in an execution state; displaying on a display a screen image for the first application program in the execution state; storing in the circuitry data on the first application program when an operation of the first application program is paused; receiving an external input to change an operation to a second application program, said external input including a dragging operation of an external device so as to pause the first application program; responding to the external input by changing the screen image on the display to a screen image of the second application program; in response to the external input, storing in the circuitry image data generated for the first application program while being executed and data of an execution state of the first application program for subsequent retrieval and display in response to another external input when resuming execution of said first application program; simultaneously displaying a partial screen image for the first application program with a partial screen image of the second application program prior to fully transitioning to a display of an entirety of the screen image for the second application program; gradually increasing a display area of the screen image for the second application program in accordance with the dragging operation; placing the second application program into an execution state when the display area of the screen image for the second application program is more than a predetermined threshold, in a case that another external input is not detected by the circuitry within a predetermined time period of displaying the entirety of the screen image for the second application program, beginning execution of the second application program; and in a case that the another external input is detected by the circuitry within the predetermined time period, not beginning execution of the second application program and subsequently beginning execution of a different application program.

10. The method of claim 9 , wherein: said responding includes changing the screen image to the screen image of the first application program, the screen image of the first application program representing one of an initial screen image of the first application program and a screen image of the execution state at a time when the circuitry caused said image data generated for the first application program to be stored.

11. The method of claim 9 , further comprising: executing, using the circuitry, instructions for said second application program after said responding so as to place said second application program into an execution state.

12. The method of claim 11 , wherein: the circuitry continues execution of instructions of said first application program after the circuitry begins execution of instructions for said second application program.

13. The method of claim 11 , wherein: when the circuitry executes the instructions for the second application program, the first application program changes to a paused state, and the display displays a screen image for the second application program while in the execution state.

14. The method of claim 13 , wherein: said plurality of application programs have respective priorities assigned thereto, and in response to said external input, images for said plurality of application programs that are in one of a paused state and an execution state are presented on said display in priority order.

15. The method of claim 9 , wherein: in response to receiving said external input, respective screens of said plurality of application programs that have been paused are displayed in an order by which said plurality of application programs were paused.

16. The method of claim 9 , wherein: in response to receiving said external input, respective screen images of said plurality of application programs that have been paused are displayed in a reverse order in which said plurality of application programs were paused.

17. A terminal apparatus comprising: circuitry configured to: store a plurality of application programs each having computer readable instructions, said plurality of application programs including a first application program and a second application program; execute instructions of the first application program; display, on a display of the terminal apparatus, a screen generated by the circuitry when executing the first application program; store data on the first application program when an operation of the first application program is paused; and respond to an external input by changing the screen to a screen image of the second application program, said external input including a touching operation of an external device so as to pause the first application program, said display being a touch display that includes the circuitry, wherein in response to the circuitry receiving the external input, the circuitry causes image data generated for the first application program while being executed and data of an execution state of the first application program to be stored for subsequent retrieval when resuming execution of said first application program into the circuitry, the circuitry simultaneously displays a partial screen image for the first application program with a partial screen image of the second application program prior to fully transitioning to a display of an entirety of the screen image for the second application program, the circuitry gradually increases a display area of the screen image for the second application program in accordance with the touching operation, and the circuitry places the second application program into an execution state when the display area of the screen image for the second application program is more than a predetermined threshold, in a case that another external input is not detected by the circuitry within a predetermined time period of displaying the entirety of the screen image for the second application program, the circuitry begins execution of the second application program, and in a case that another external input is detected by the circuitry within the predetermined time period, the circuitry does not begin execution of the second application program and the circuitry subsequently begins execution of a different application program.

18. The apparatus of claim 1 , wherein: the external device includes a finger.

19. The apparatus of claim 1 , wherein: the circuitry places the second application program into the execution state when a width of the display area of the screen image for the second application program is more than a predetermined threshold.

20. The method of claim 9 , wherein: the external device includes a finger.